In the late 1950s, the United States government acquired Mount Umunhum to build Almaden Air Force Station, an early warning radar facility that operated from 1957 to 1980 as part of a West Coast network scanning 250 miles over the Pacific Ocean for possible airborne nuclear attacks from Soviet bombers during the Cold War. Almaden Air Force Station and other Bay Area military bases employed technologically inclined people for Cold War service, and as many as 125 military personnel and their families lived and worked on Mount Umunhum among dozens of structures that housed equipment, a commissary, food services, living quarters, and recreational facilities including a bowling alley and swimming pool. The 84.5-foot-tall concrete tower that remains was the foundation for one of the largest rotating military radars ever built, linked with similar stations in California and hundreds across the country that fed surveillance data into the Semi-Automatic Ground Environment defense system, where powerful computers and networking equipment coordinated signals, assessed potential threats, and directed response through the North American Aerospace Defense Command. Advances in missile delivery systems and satellite technology, including work by some of the same people who came to Almaden Air Force Station, eventually made the radar obsolete and led to the station’s permanent closure in 1980, after which many former Air Force personnel stayed in the region and applied their skills to the development of Silicon Valley as a world leader in technology and innovation.
